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Rounding Off and Estimation Worksheet

Mental maths lesson 15: Rounding off and best estimate · Set 759 · 40 questions
TalentJR

How to do it in your head (Round, then work): Round each number: 2-digit numbers to the nearest ten, 3-digit numbers to the nearest hundred. Do the easy sum with the round numbers. Choose the option closest to your estimate.

NameDateTime takenScore ___ / 40
  1. 1.Best estimate of 93 × 51? (a) 4500 (b) 450 (c) 45000
  2. 2.Best estimate of 187 + 787? (a) 1200 (b) 800 (c) 1000
  3. 3.Best estimate of 63 × 63? (a) 360 (b) 3600 (c) 36000
  4. 4.Best estimate of 858 + 271? (a) 1000 (b) 1400 (c) 1200
  5. 5.Best estimate of 575 + 176? (a) 1000 (b) 800 (c) 600
  6. 6.Best estimate of 21 × 29? (a) 60 (b) 600 (c) 6000
  7. 7.Best estimate of 68 × 36? (a) 280 (b) 28000 (c) 2800
  8. 8.Best estimate of 93 × 54? (a) 450 (b) 4500 (c) 45000
  9. 9.Best estimate of 488 + 295? (a) 800 (b) 1000 (c) 600
  10. 10.Best estimate of 346 + 421? (a) 700 (b) 500 (c) 900
  11. 11.Best estimate of 68 × 81? (a) 56000 (b) 5600 (c) 560
  12. 12.Best estimate of 42 × 36? (a) 16000 (b) 1600 (c) 160
  13. 13.Best estimate of 314 + 851? (a) 1000 (b) 1200 (c) 1400
  14. 14.Best estimate of 203 + 390? (a) 600 (b) 800 (c) 400
  15. 15.Best estimate of 764 + 631? (a) 1600 (b) 1200 (c) 1400
  16. 16.Best estimate of 76 × 46? (a) 40000 (b) 400 (c) 4000
  17. 17.Best estimate of 16 × 27? (a) 6000 (b) 60 (c) 600
  18. 18.Best estimate of 217 + 316? (a) 500 (b) 300 (c) 700
  19. 19.Best estimate of 83 × 26? (a) 24000 (b) 2400 (c) 240
  20. 20.Best estimate of 91 × 19? (a) 18000 (b) 1800 (c) 180
  21. 21.Best estimate of 71 × 56? (a) 4200 (b) 42000 (c) 420
  22. 22.Best estimate of 19 × 16? (a) 4000 (b) 400 (c) 40
  23. 23.Best estimate of 67 × 33? (a) 210 (b) 21000 (c) 2100
  24. 24.Best estimate of 26 × 59? (a) 180 (b) 18000 (c) 1800
  25. 25.Best estimate of 37 × 37? (a) 16000 (b) 160 (c) 1600
  26. 26.Best estimate of 362 + 152? (a) 600 (b) 800 (c) 400
  27. 27.Best estimate of 54 × 66? (a) 3500 (b) 35000 (c) 350
  28. 28.Best estimate of 865 + 237? (a) 1100 (b) 1300 (c) 900
  29. 29.Best estimate of 798 + 251? (a) 1300 (b) 900 (c) 1100
  30. 30.Best estimate of 71 × 53? (a) 35000 (b) 3500 (c) 350
  31. 31.Best estimate of 192 + 257? (a) 500 (b) 700 (c) 300
  32. 32.Best estimate of 54 × 89? (a) 4500 (b) 450 (c) 45000
  33. 33.Best estimate of 170 + 822? (a) 1000 (b) 1200 (c) 800
  34. 34.Best estimate of 610 + 772? (a) 1400 (b) 1600 (c) 1200
  35. 35.Best estimate of 298 + 264? (a) 800 (b) 400 (c) 600
  36. 36.Best estimate of 50 × 42? (a) 200 (b) 2000 (c) 20000
  37. 37.Best estimate of 157 + 366? (a) 800 (b) 400 (c) 600
  38. 38.Best estimate of 91 × 71? (a) 6300 (b) 63000 (c) 630
  39. 39.Best estimate of 398 + 760? (a) 1000 (b) 1200 (c) 1400
  40. 40.Best estimate of 175 + 377? (a) 400 (b) 600 (c) 800

Answer key

  1. 4500
  2. 1000
  3. 3600
  4. 1200
  5. 800
  6. 600
  7. 2800
  8. 4500
  9. 800
  10. 700
  11. 5600
  12. 1600
  13. 1200
  14. 600
  15. 1400
  16. 4000
  17. 600
  18. 500
  19. 2400
  20. 1800
  21. 4200
  22. 400
  23. 2100
  24. 1800
  25. 1600
  26. 600
  27. 3500
  28. 1100
  29. 1100
  30. 3500
  31. 500
  32. 4500
  33. 1000
  34. 1400
  35. 600
  36. 2000
  37. 600
  38. 6300
  39. 1200
  40. 600

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